Inter-sexual and inter-seasonal differences in the chemical signalling strategies of brown bears

The brown bear (Ursus arctos) is a species which, due to its solitary, dominance hierarchy social system and large home range, is thought to rely heavily on chemical signals as a means of communication. Through camera traps orientated towards bear ‘rub trees’ over a two-year period, we assessed the proportional contribution of scent marking in different seasons by different age sex classes, and gained insights into the role of chemical signalling in maintaining social structure. We found, during the breeding season (June-July), that both adult males (n=38 P1 year (n=11 P=0.003) scent marked trees significantly more often than expected, whereas lone adult females (n=7) and subadults (n=3) marked less than expected. Outside of the breeding season (August-October), adult males (n=70) marked in an expected proportion, females with cubs (all ages) marked significantly more than expected (n=71 P<0.001), and lone adult females (n=11) and subadults (n=15) marked less than expected. During both the breeding season (n=7 P=0.026) and the fall (n=11 P<0.001), adult females marked trees significantly less than their occurrence on bear trails would expect, as did subadults during the breeding season (n=3 P=0.026) but not during the fall (n=15). Adult males marked at significantly high frequencies both during and outside of the breeding season, potentially to communicate dominance between males. Supported by the low frequency of scent marking by subadults. We observed a total avoidance of bear trails containing active rub trees by females with cubs <1 year during the breeding season, a possible counterstrategy to sexually selected infanticide due to the strong male bias in scent marking during the breeding season. We hypothesize that scent marking in brown bears is taught by the mother, beginning with cubs <1 year outside of the breeding season at a relatively ‘safe’ time of year

An investigation of the olfactory and multi-modal communication of African lions (Panthera leo) in the Okavango Delta, Botswana

Communication is a crucial mechanism at the basis of animal social behaviour and likely to be of central importance in facilitating the evolution of complex animal societies. This thesis aims to expand our knowledge of the olfactory, vocal and multi-modal communication of wild African lions. Much of our understanding of lion behaviour originates from studies in East Africa, yet the ancestral lion may have been a wetland specialist in habitats such as the Okavango Delta. Here I first employ an established playback design to test whether lions can determine the number of conspecifics calling in large vocal choruses, demonstrating that the upper limit for lions to assess the number of simultaneous callers is three, matching the ability of humans performing a similar task. I then use a novel playback experiment to demonstrate that lions are capable of cross-modal processing of information on individual identity; an ability originally thought to be unique to humans and not previously demonstrated in wild animal populations. Next, I provide a novel and detailed investigation into the olfactory communication of lions. First I analyse the scent-marking of lions and the responses of group members to marks, and demonstrate that chemical signals may play an important role in the social lives of prides. I then use a scent presentation experiment to test the function of urinary scent-marks in communication within and between prides, determining that lion urine signals the social group and sex of the depositor and may be important for sexual assessment and territory defence. Overall this thesis significantly advances our knowledge of the vocal and olfactory communication of African lions, and provides the first evidence that lions are capable of cross-modal individual recognition during communication between conspecifics. Together these results highlight that olfactory and multi-modal communication are important for lions, despite being previously overlooked

The nature and function of human nonverbal vocalisations

Though human nonverbal vocalisations are widespread, scientific consideration of their mechanisms and communicative functions has been largely overlooked. This is despite their close alignment with the vocal communicative systems of primates and other mammals, whose primary function is to signal indexical information relevant to sexual and natural selection processes. In this thesis, I examine human nonverbal vocalisations from an evolutionary perspective, with the central hypothesis that they are functionally and structurally homologous to nonhuman mammal calls, communicating evolutionarily relevant indexical information that is perceived and utilised by listeners. In Chapter 1, I introduce the methodological framework (source-filter theory) necessary to understand the production of vocal signals in mammals, before summarising the information contained within the acoustic structure of nonhuman mammals and human speech, and the effects these cues have on both vocaliser and listener. I then examine the current evidence for functional and structural homology between human and nonhuman nonverbal vocalisations. In Chapters 2 to 5, I quantitatively analyse the acoustic structure of a number of nonverbal vocalisations, and perform playback experiments to examine their functional effects on listeners. In Chapters 2 and 3, I investigate whether aggressive roars and distress screams communicate acoustic cues to absolute and relative strength and height. In Chapter 4, I analyse the acoustic structure of pain cries of varying intensity, and conduct playback experiments to explore the acoustic and perceptual correlates of pain. In Chapter 5, I examine whether the fundamental frequency of tennis grunts produced during professional tennis matches is dependent on the sex and body posture of the vocaliser, as well as the progress and outcome of the contest, and whether listeners can infer these cues. In Chapter 6, I tie these findings together, arguing that the acoustic structure of human nonverbal vocalisations, in continuity with nonhuman mammal vocalisations, has been selected to support the functional communication of indexical and motivational information

Expression of gender in the human voice: investigating the “gender code”

We can easily and reliably identify the gender of an unfamiliar interlocutor over the telephone. This is because our voice is “sexually dimorphic”: men typically speak with a lower fundamental frequency (F0 - lower pitch) and lower vocal tract resonances (ΔF – “deeper” timbre) than women. While the biological bases of these differences are well understood, and mostly down to size differences between men and women, very little is known about the extent to which we can play with these differences to accentuate or de-emphasise our perceived gender, masculinity and femininity in a range of social roles and contexts. The general aim of this thesis is to investigate the behavioural basis of gender expression in the human voice in both children and adults. More specifically, I hypothesise that, on top of the biologically determined sexual dimorphism, humans use a “gender code” consisting of vocal gestures (global F0 and ΔF adjustments) aimed at altering the gender attributes conveyed by their voice. In order to test this hypothesis, I first explore how acoustic variation of sexually dimorphic acoustic cues (F0 and ΔF) relates to physiological differences in pre-pubertal speakers (vocal tract length) and adult speakers (body height and salivary testosterone levels), and show that voice gender variation cannot be solely explained by static, biologically determined differences in vocal apparatus and body size of speakers. Subsequently, I show that both children and adult speakers can spontaneously modify their voice gender by lowering (raising) F0 and ΔF to masculinise (feminise) their voice, a key ability for the hypothesised control of voice gender. Finally, I investigate the interplay between voice gender expression and social context in relation to cultural stereotypes. I report that listeners spontaneously integrate stereotypical information in the auditory and visual domain to make stereotypical judgments about children’s gender and that adult actors manipulate their gender expression in line with stereotypical gendered notions of homosexuality. Overall, this corpus of data supports the existence of a “gender code” in human nonverbal vocal communication. This “gender code” provides not only a methodological framework with which to empirically investigate variation in voice gender and its role in expressing gender identity, but also a unifying theoretical structure to understand the origins of such variation from both evolutionary and social perspectives

Improving individual identification of wolves (Canis lupus) using the fundamental frequency and amplitude of their howls: a new survey method

Many bioacoustic studies have been able to identify individual mammals from variations in the fundamental frequency (F0) of their vocalizations. Other characteristics of vocalization which encode individuality, such as amplitude, are less frequently used because of problems with background noise and recording fidelity over distance. In this thesis, I investigate whether the inclusion of amplitude variables improves the accuracy of individual howl identification in captive Eastern grey wolves (Canis lupus lycaon). I also explore whether the use of a bespoke code to extract the howl features, combined with histogram-derived principal component analysis (PCA) values, can improve current individual wolf howl identification accuracies. From a total of 89 solo howls from six captive individuals, where distances between wolf and observer were short, I achieved 95.5% (+9.0% improvement) individual identification accuracy of captive wolves using discriminant function analysis (DFA) to classify simple scalar variables of F0 and normalized amplitudes. Moreover, this accuracy was increased to 100% when using histogram-derived PCA values of F0 and amplitudes of the first harmonic

Improving the accuracy and efficiency of bird song analysis with machine learning based event detection

Ornithology is an exciting field with novel research emerging everyday. Researchers in bioacoustics often spend hours within the wilderness recording bird calls to analyze later in their lab. The burden of sifting through hours of audio recordings from the field continues to remain a time-consuming and manual task, despite the inherent value of such research. In this work, we investigate the ability of a mobile application to provide an accelerated method for ornithologists to upload acoustic field recordings for analysis. Driven by recent advancements in technology, there is a growing need for innovative solutions that can streamline this research process. Our proposed solution integrates machine learning algorithms with bioacoustic signal processing with the goal of accelerating the process of analyzing hours of field recordings. In this thesis, we focus on the integration of future machine learning algorithms into an event detection pipeline. This larger project involves three separate parts: (1) the user interface and back end architecture developed by a small team of students for the Oregon State CS 46x capstone series, (2) an event detection algorithm completed as a synergistic extension of the capstone, and (3) a machine learning system developed as part of a graduate thesis. Together, these projects integrate to enhance the accuracy and efficiency of bioacoustic event detection by leveraging machine intelligence with deep learning. Furthermore, we evaluate the performance of these approaches using real-world datasets and discuss our approach in the context of traditional event detection techniques. This research project contributes valuable insights into the feasibility and effectiveness of integrating machine learning algorithms into a cloud-based acoustic event detection pipeline and highlights the potential benefits of this integration for various applications to expedite time-consuming bioacoustic research processes.Key Words: audio processing, bioacoustics, bird song, event detection, databas

Pacific Symposium on Biocomputing 2023

The Pacific Symposium on Biocomputing (PSB) 2023 is an international, multidisciplinary conference for the presentation and discussion of current research in the theory and application of computational methods in problems of biological significance. Presentations are rigorously peer reviewed and are published in an archival proceedings volume. PSB 2023 will be held on January 3-7, 2023 in Kohala Coast, Hawaii. Tutorials and workshops will be offered prior to the start of the conference.PSB 2023 will bring together top researchers from the US, the Asian Pacific nations, and around the world to exchange research results and address open issues in all aspects of computational biology. It is a forum for the presentation of work in databases, algorithms, interfaces, visualization, modeling, and other computational methods, as applied to biological problems, with emphasis on applications in data-rich areas of molecular biology.The PSB has been designed to be responsive to the need for critical mass in sub-disciplines within biocomputing. For that reason, it is the only meeting whose sessions are defined dynamically each year in response to specific proposals. PSB sessions are organized by leaders of research in biocomputing's 'hot topics.' In this way, the meeting provides an early forum for serious examination of emerging methods and approaches in this rapidly changing field

Exploring Animal Behavior Through Sound: Volume 1

This open-access book empowers its readers to explore the acoustic world of animals. By listening to the sounds of nature, we can study animal behavior, distribution, and demographics; their habitat characteristics and needs; and the effects of noise. Sound recording is an efficient and affordable tool, independent of daylight and weather; and recorders may be left in place for many months at a time, continuously collecting data on animals and their environment. This book builds the skills and knowledge necessary to collect and interpret acoustic data from terrestrial and marine environments. Beginning with a history of sound recording, the chapters provide an overview of off-the-shelf recording equipment and analysis tools (including automated signal detectors and statistical methods); audiometric methods; acoustic terminology, quantities, and units; sound propagation in air and under water; soundscapes of terrestrial and marine habitats; animal acoustic and vibrational communication; echolocation; and the effects of noise. This book will be useful to students and researchers of animal ecology who wish to add acoustics to their toolbox, as well as to environmental managers in industry and government

Exploring Animal Behavior Through Sound: Volume 1

This open-access book empowers its readers to explore the acoustic world of animals. By listening to the sounds of nature, we can study animal behavior, distribution, and demographics; their habitat characteristics and needs; and the effects of noise. Sound recording is an efficient and affordable tool, independent of daylight and weather; and recorders may be left in place for many months at a time, continuously collecting data on animals and their environment. This book builds the skills and knowledge necessary to collect and interpret acoustic data from terrestrial and marine environments. Beginning with a history of sound recording, the chapters provide an overview of off-the-shelf recording equipment and analysis tools (including automated signal detectors and statistical methods); audiometric methods; acoustic terminology, quantities, and units; sound propagation in air and under water; soundscapes of terrestrial and marine habitats; animal acoustic and vibrational communication; echolocation; and the effects of noise. This book will be useful to students and researchers of animal ecology who wish to add acoustics to their toolbox, as well as to environmental managers in industry and government